Interview Questions - Networking (Cisco/Juniper/Citrix , etc)

QoS Questions

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1. Shaper vs Policer

2. Usecase SrTCM vs TrTCM

3. Algorithmic explanation of SrTCM vs TrTCM

4. How WRED works ?

5. Color aware WRED and Precedence management ?

6. DWRR vs WRR ? 

7. How to load share among queues using Weights and different QoS Algorithms ?

8. Why do you need "trust COS" port-level configuration? is it going to prevent all the attacks ? 

ASIC and Network Questions:

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1. broadcom XGS pipeline

2. How L2 gets forwarded.

3. On Ethernet header what decides the next protocol ? If ethertype is used for something else too, what is it for ?

4. Can you draw a frame and it's fields and their significants for: Ethernet+double-tag VLAN + IPv4 header

Operating Systems:

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1. Mutex Vs Semaphore

2. IPC mechanisms : Signal Handling Basics, Socket Programming (NETLINK vs RAW SOCKET), 

3.Thread safe programming

4. Memory Layout of Process vs Thread. 

Design Questions:

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1. What Datastructure will you use for MAC table and IP routing table ? explain in detail about your decisions. 

2. How do you breakdown a problem: say for example if the current scenario of Covid-19 lockdown needs to be relaxed slowly over the weeks. how do you do it ? 

3. What is the difficult problem that you have faced recently and how did you solve it and talk about it .

C Programs:

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1. Endianness of the system

2. HTONS and NTOHS function

3. Height of a Binary tree

4. Reverse a linked list

Few Must DOs:

1. Watch this even if you know everything in basic Networking : https://www.youtube.com/playlist?list=PL8hvAJ8ypAInbY-qmtZ9RG0d7IpAkS7Dy

2. How does traceroute work https://networklessons.com/cisco/ccna-routing-switching-icnd1-100-105/traceroute 

Data Structures and Algorithms

Big O notation:

- Worst case execution complexity

O(1) : access the data at first lookup

O(n) : lookup a data in a list of n items (linear complexity).

O(n^2): nested loops(2loops)

O(n!) : loop for each item in the list of data

- Space complexity

Good code:

- Readable

- Scalable (speed and Memory)

For Quick Overview : https://drive.google.com/drive/folders/1t75vJEgzndUVp_Jndh9O7tPN9xTu5s57?usp=sharing

For Distributed design : http://book.mixu.net/distsys/intro.html

Google Interview Prep Requirements : http://steve-yegge.blogspot.com/2008/03/get-that-job-at-google.html

P-NP readings : https://www.quora.com/How-do-you-explain-NP-Complete-and-NP-hard-to-a-child and https://stackoverflow.com/questions/1857244/what-are-the-differences-between-np-np-complete-and-np-hard